| 摘要 |
<p>An elongate framing member (2, 6) with a U or C shaped cross-section has a pair of mutually parallel side walls (12, 14) which extend in a common direction from opposite edges of a base wall (13, 15). At least one of the walls has a through hole (20, 21) that can be surrounded by a dimple that is offset out of the general plane of the respective wall. Such framing members can be joined together to form a frame, e.g. a triangular roof truss, by fitting a fastener through the through-holes of respective framing members. The dimples facilitate pre-alignment of the through holes prior to fitting the fastener, by nesting the dimples of respective framing members inside one another. The fastener may, for example, be a self-tapping screw, a rivet, or a threaded bolt (24) and nut (26), the bolt shank passing through a spacer sleeve (22) and through pairs of transversely aligned through-holes (20, 21) in the side walls (12, 14) of each chord (2, 6).</p> |
